|Classification and external resources|
Chloracne is an acne-like eruption of blackheads, cysts, and pustules associated with over-exposure to certain halogenated aromatic compounds, such as chlorinated dioxins and dibenzofurans. The lesions are most frequently found on the cheeks, behind the ears, in the armpits and groin region.
The condition was first described in German industrial workers in 1897 by von Bettman, and was initially believed to be caused by exposure to toxic chlorine (hence the name "chloracne"). It was only in the mid-1950s that chloracne was associated with aromatic hydrocarbons. The substances that may cause chloracne are now collectively known as chloracnegens.
Chloracne is particularly linked to toxic exposure to dioxins (byproducts of many chemical processes, including the manufacture of herbicides such as Agent Orange)—so much so that it is considered a clinical sign of dioxin exposure. The severity and onset of chloracne may follow a typical asymptotic dose-response relationship curve.
Etiology and progression 
Chloracne normally results from direct skin contact with chloracnegens, although ingestion and inhalation are also possible causative routes.
Chloracnegens are fat-soluble, meaning they persist in the body fat for a very long period following exposure. Chloracne is a chronic inflammatory condition that results from this persistence, in combination with the toxin's chemical properties. It is believed, at least from rodent models, that the toxin activates a series of receptors promoting macrophage proliferation, inducing neutrophilia and leading to a generalised inflammatory response in the skin. This process may also be augmented by induction of excess tumor necrosis factor in the blood serum.
The inflammatory processes lead to the formation of keratinous plugs in skin pores, forming yellowish cysts and dark pustules. The associated pus is usually greenish in color. The skin lesions occur mainly in the face, but in more severe cases they involve the shoulders and chest, the back, and the abdomen. In advanced cases, the lesions appear also on the arms, thighs, legs, hands and feet.
Once chloracne has been identified, the primary action is to remove the patient and all other individuals from the source of contamination. Further treatment is symptomatic.
The course of the disease is highly variable. In some cases the lesions may resolve within two years or so; however, in other cases the lesions may be effectively permanent (mean duration of lesions in one 1984 study was 26 years, with some workers remaining disfigured over three decades after exposure).
Recent research by groups at University of Cincinnati School of Medicine in Ohio and the University of Western Australia indicated that PCB poisoning, including chloracne symptoms, can be treated with fat substitute olestra.
Related conditions 
Notable cases 
- In 1949, 226 workers became ill after a container of herbicide exploded at a Monsanto Company plant in Nitro, West Virginia. Many were diagnosed with chloracne; a medical report at the time described "systemic intoxication in the workers involving most major organ systems."
- 193 cases of chloracne occurred in Seveso, Italy in 1976 following an industrial accident in which up to a few kilograms of TCDD were released into the atmosphere.
- Thousands  of individuals were exposed at Fort McClellan Alabama,when a chemical weapons training center and a nearby Monsanto factory disposed of chemicals into a west Anniston creek over several decades. Many people settled out of court, but a class-action suit is still ongoing. Although the incineration of the chemical weapons at Fort McClellan ended in 2011, areas of the base remain closed or off-limits due to the residual contamination. A significant percentage of soldiers who trained or were stationed at Fort McClellan have chloracne and many of those maintain that chemical weapons were tested on them.
- Almost 2,000 individuals suffered chloracne, among other symptoms, after chronic exposure to cooking oils contaminated with PCBs and PCDFs in northern Kyūshū, Japan in 1968. The syndrome came to be called Yusho or "Rice Oil" disease.
- In 1979, a similar case of mass contamination of cooking oil was reported in central Taiwan. Over 2,000 individuals were affected by what came to be called Yu-Cheng.
- Ukrainian President Viktor Yushchenko suffered from prominent facial chloracne after being diagnosed with possible dioxin poisoning in late 2004 according to prominent toxicologist John Henry, though he never personally examined Yushchenko.
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